President Bush led the praise for six-time Tour de France winner Lance Armstrong by calling his fellow Texan's efforts "awesome".
The President phoned Armstrong moments after he had wrapped up his sixth-straight overall win in Paris.
Fellow American Tyler Hamilton was also quick to hail Armstrong's achievements, saying his feat would never be matched.
"To win six Tours in a row is truly incredible - I don't think anyone will do it again," said Hamilton.
Armstrong netted his historic sixth victory by more than six minutes from second-placed rider Andreas Kloden.
Tour de France director Jean-Marie Leblanc also paid homage to Armstrong, but said he was not unbeatable.
"He's the only one to have won it six times," said Leblanc.
"He won stages of all kinds, time trials, mountain stages - he's an accomplished
champion but he's not invincible."
King of the Mountains winner Richard Virenque, who once finished second to Armstrong overall, admitted he had changed his tactics because of the American.
"When I saw the way Lance started winning the Tour, I knew it was useless going for overall victory," he said.
"I went back to chasing the King of the Mountains jersey - and I'm glad I did."
Third-placed finisher Ivan Basso paid his own tribute to Armstrong but vowed to win the event one day.
"Armstrong was impressive. He won every stage he could in the mountains and the time trials, showing yet again he is the best rider in the world," the Italian said.
"But one of the reasons I'm happy with my Tour was that I was the only rider to stay with him in the first two weeks and was even a little bit stronger than him in the Pyrenees.
"I have seven or eight Tours de France ahead of me. I know I will win it one day."